Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/983801
• Three years ago, we secured SGD $2.5 million from the Singapore government to develop our forward osmosis (FO) technology. It was part of a larger pot of investment in research and development (R&D) at that time by the Environment & Water Industry O‚ ce. The title of the project is 'Aqua- porin based biomimetic forward osmosis mem- branes: from lab scale production of membranes to pilot production and industrial test bedding of membrane modules'. It began with very small lab membranes, about half the size of an A4 sheet of paper, optimising the technology. The next stage was to upscale our technology, to have bigger membranes, and to go into an industrial-size pilot, which is what we have now. The project is in its Ž nal stage, where we are piloting the technology. • With Darco, we are piloting an FO treatment for wastewater from the semi-conductor industry, in Malaysia. The challenge is that the water has been polluted with heavy metals and certain other contaminants that make it di‚ cult for conven- tional water treatment systems to deal with it. Conventionally, you use a lot of chemicals to treat these waters and there can be a challenge in dosing them correctly. With FO, we replace all the chemical treatment with a single membrane step. In re- verse osmosis (RO) you use hydraulic pressure, meaning that foulants, heavy metals or organics that are present in the feed are driven into the membrane surface. FO works with osmotic pressure; it's a di• usion-based process so there is no hydraulic pressure involved, making the foulants easier to remove. • The project ends in November 2018, when we will have the full data. So far, we've seen that using FO, we can directly treat wastewaters with levels of chemical oxygen demand (COD) at 50,000 parts per million (ppm). That's very signiŽ - cantly higher than a conventional RO membrane, which may be around 10 ppm. It's just one example of how FO widens the range of what you can treat with a membrane. • One common misconception is that FO can be used for de- salination or drinking water puriŽ cation. FO doesn't produce clean drinking water because the driving force is an osmotic gradient. On one side of an FO membrane you have whatever you want to concentrate, or de-water, and on the other side you have a high total dissolved solids (TDS) solution. That could be seawater or something similar. The clean water that is extracted from whatever you have on the feed side goes into the high osmotic, high concentration solution on the other side of the membrane. You don't get clean water out directly; rather it dilutes the concentration of the solution on the other side. To get the clean water out you need an RO to regenerate the osmotic solution. FO is a potential pre-treatment for RO: It eliminates all the typical pre-treatment steps you need before anything can hit an RO membrane, by dealing with it directly. Q & A M A R K P E R RY "FO widens the range of what you can treat with a membrane" Mark Perry is Aquaporin Asia vice presid ent of business development What's the challenge of semi- conductor wastewaters? What have you learned so far? Can you use it for drinking water applications? What's the background to your research? Q & A M A R K P E R RY "FO widens the range of what you can treat with a membrane" "FO is a potential pre-treatment for RO" Water. desalination + reuse June 2018 In Site 23 VIETNAM • Support for structuring DBOO was pivotal to deal • Darco's first project in Vietnam • The four plants will take river water and brackish water and clean it to potable standards DARCO WINS DBOO FOR FOUR WATER PLANTS Darco Water Technologies of Singapore, and InfraCo Asia Development are partnering on a design, build, own, operate (DBOO) project covering four municipal water treatment plants in Vietnam. The two com- panies were brought together by International Enterprise (IE) Singapore, a government agency that promotes Singapore compa- nies in trading and collaborat- ing overseas. The plants will take feed- water from rivers and treat it to potable standards, with capacity of 62,000 m3/d across all four of them. The Ž rst facility, a 15,000 m3/d plant in Ben Tre province, begins construction in Q4 2017, and will provide water to in- dustry and domestic customers. One of the plants in southern Vi- etnam is subject to a feasibility study to establish whether the treatment required is for brack- ish water, because seawater has started to mix with the river. Darco will treat river water to potable stands in Ben Tre, a coastal province in the Mekong Delta of southern Vietnam